Late Pleistocene (Rancholabrean) mammals from fissure deposits in the Jurassic Todilto Formation, White Mesa mine, Sandoval County, north-central New Mexico

Abstract

A late Pleistocene ( Rancholabrean) fossil site containing partial to nearly complete articu lated skeletons of large mammals preserved in fissure deposits was discovered in 2005 at the White Mesa mine near San Ysidro in San doval County, north-central New Mexico. The fissures are in gypsum of the Jurassic Todilto Formation. Structural analysis suggests the fissures opened to the surface during the Pleistocene in response to extension associ ated with the Rio Grande rift. Bones were found approximately 9–12 m (30–40 ft) below the modern land surface in three different fis sures within approximately a 15-m (~50-ft) radius. Four species of large mammals are preserved in the fissures, each known from at least one partial to nearly complete skeleton: stilt-legged horse ( Equus cf. E. francisci), camel (Camelops hesternus), extinct bison (Bison antiquus), and mule deer ( Odocoileus hemionus).